The Metropolitan Police installed the bollards overnight on the land which links Constitution Hill and Green Park.

Bollards are used in the UK to prevent traffic and vehicles from entering certain areas.

After a car rammed into pedestrians on Westminster Bridge this week, the measures are likely put in place to prevent a vehicle from mounting the pavement outside of the Palace.

The police have stressed that these installations are not a result of specific intelligence about attacks outside of the Palace, but are there to protect a tourist spot.

A spokesperson said: “It’s security measures put in place but not in response to any threat. Buckingham Palace is obviously a high profile area that is going to benefit from them.”

In addition to the bollards, steel barriers have also been placed in the Mall which leads up to The Queen’s Central London residence.

Buckingham Palace has declined to comment on the new security arrangements.

Four people were killed and more than 50 people were injured during Wednesday’s terror attack.

After ramming into pedestrians on Westminster Bridge, the 52-year-old terrorist stabbed a police officer, 48-year-old PC Keith Palmer, who later died.

Aysha Frade, a college tutor, and Kurt Cochran, an American tourist who was celebrating his 25th wedding anniversary also lost their lives.

75-year-old Leslie Rhodes from South London was named on Friday morning as the fourth fatality after succumbing to his injuries in hospital.

Prime Minister Theresa May chaired an emergency COBRA meeting, where afterwards she condemned the “sick and depraved terrorist attack.”

Speaking outside of Number 10, Mrs May said: “Let me make it clear today… any attempt to defeat those values through violence is doomed to failure.

“Parliament will come together as normal and Londoners will get up and go about their day as normal… they will walk these streets, they will live their lives never giving into terror and never allowing the voices of hate and evil to drive us apart.”